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用清除有机自由基DPPH法评价市售腐乳提取物的抗氧化能力 总被引:7,自引:0,他引:7
用清除1,1-二苯基-2-苦基苯肼(DPPH)自由基能力表示腐乳提取物的抗氧化能力,并以抗氧化剂(α-生育酚)为当量浓度表示抗氧化的能力大小。中国市售14种腐乳的水提取物的抗氧化活性为2.03~11.93μgα-生育酚/mg,50%乙醇提取物的抗氧化活性为0.75~4.94μgα-生育酚/mg。14种腐乳提取物的总抗氧化活性为2.91~16.87μgα-生育酚/mg)。贵州的“老干爹”和福建的“米酱豆腐乳”均显出最大的活性。 相似文献
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The effects of 0, 100, 250, 500, 750 or 1000 ppm Trolox and ascorbic acid on the singlet oxygen oxidation of aromatic amino acids viz. phenylalanine, tryptophan, tyrosine in the presence of 25 ppm riboflavin were determined by measuring depleted headspace oxygen by gas chromatography and aromatic amino acid content by high performance liquid chromatography. The coefficients of variations (CVs) for headspace oxygen analysis and HPLC analysis of aromatic amino acids were 1.4% and 4.7%, respectively. Samples were stored under light (1000 lux) at 30 °C for 10 h. Both Trolox and ascorbic acid acted as antioxidants. As the concentration of Trolox and ascorbic increased from 0 to 1000 ppm, the head space oxygen depletion increased. This was due to the oxidation of Trolox and ascorbic acid along with amino acids in the presence of riboflavin. High performance liquid chromatography analysis of the samples clearly indicated that both Trolox and ascorbic acid minimised the degradation of phenylalanine, tryptophan, tyrosine significantly (p < 0.05), but did not prevent their oxidation completely. Trolox acted as a better antioxidant than ascorbic acid in protecting phenylalanine, tryptophan and tyrosine. Type-I mechanism was mainly responsible for riboflavin photosensitised degradation of aromatic amino acids. 相似文献
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A reappraisal of traditional apple cultivars from Southern Italy as a rich source of phenols with superior antioxidant activity 总被引:1,自引:0,他引:1
Lucia Panzella Milena Petriccione Pietro Rega Marco Scortichini Alessandra Napolitano 《Food chemistry》2013
Few literature data are available on the nutraceutical properties of little widespread local apple cultivars. Such lack of information prevents exploitation of these germplasms for genetic improvement of new cultivars and for the re-evaluation of local agricultural products, which may attract a large share of consumers oriented towards natural food evoking ancient flavours. In this work eight traditional apple cultivars of Southern Italy were analysed in terms of phenolic composition and free radical scavenging activity in comparison with commercial “Annurca” and “Gold Chief® Gold Pink∗” cultivars. HPLC-UV-MS analysis of methanol extracts of the cultivars under examination showed significant differences in phenol distribution within the three main classes of hydroxycinnamates, dihydrochalcones, and flavan-3-ols. Such differences were found to be associated with the antioxidant activities as determined by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. A good correlation was observed between the percentage of reduced DPPH and the total phenol content (R = 0.79). Among all phenol classes, the flavan-3-ol content showed the highest correlation (R = 0.77). Almost all of the traditional cultivars examined exhibited a much higher phenol content (2- to 7-fold) and hydrogen donor activity (1.5- to 4-fold) than widely consumed cultivars like “Annurca” and “Gold Chief® Gold Pink∗”. 相似文献
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高效液相色谱法测定葡萄酒的有机酸及乙酸 总被引:5,自引:0,他引:5
采用高效液相色谱法同时测定葡萄酒中的有机酸和乙酸。根据色谱柱的特点优化了分离条件,根据葡萄酒的特性进行了相应的预处理,得出了分离良好的色谱图,各组分相对标准偏差(n=5)为1.5%-3.3%,平均回收率为93.9%-98.5%,达到了分析方法的要求。 相似文献
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Ascorbic and dehydroascorbic acids (vitamin C), tocopherols (vitamin E) and unsaturated fatty acids are heat-sensitive and therefore, their concentrations in human milk could be affected by pasteurisation. Here we determined the concentrations of ascorbic acid plus dehydroascorbic acid, ascorbic acid alone, and α- and γ-tocopherols, and the percentages of fatty acids in samples of human milk after pasteurisation by a slow (62.5 °C, 30 min) or fast heating (100 °C, 5 min) procedure. Both methods led to a significant decrease in the concentrations of ascorbic acid plus dehydroascorbic acid (12% and 29%), ascorbic acid (26% and 41%), α-tocopherol (17% and 34%) and γ-tocopherol (13% and 32%), respectively. However, milk fatty acids, including the polyunsaturated long-chain fatty acids, were unaffected by the two methods. On the basis of these observations, we recommend that human milk be treated using a slow pasteurisation. In addition, we propose ascorbic acid as a marker of the degree of heat treatment. 相似文献
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The biological activity of lycopene can be enhanced by the presence of these other active antioxidants such as β-carotene, vitamin E, and vitamin C. Since many of these natural antioxidants are consumed together in foods, the potential for synergistic interactions is high in the human diet. The aim of this study was to determine what concentrations and combinations of antioxidants among lycopene, vitamin E, vitamin C, and β-carotene are capable of producing synergistic antioxidant effects, based on tomato-based food products. Solutions of the scavenging capacities of lycopene, vitamin E, vitamin C, and β-carotene, alone and in different combinations were measured using the stable free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) method. Three different levels of each antioxidant were used. A comparison of the scavenging capacity (antioxidant activity) of the combinations of antioxidants to the arithmetic sum of the scavenging capacities of the individual antioxidants was used to calculate the synergistic effects (SEs) between the antioxidants. The results showed that the mixture that had the highest SEs (P<0.01) was the solution combining lycopene (15 μmol/L), vitamin E (5.0 μmol/L), vitamin C (0.16 μmol/L), and β-carotene (10.83 μmol/L). The results suggest that the antioxidant property of this combination was substantially superior to the sum of the individual antioxidant effects, and these interactions can enhance the antioxidant effectiveness of natural antioxidants. The results could guide in the formulation and development of functional food products that have high antioxidant potential. 相似文献
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Alcalase降解水不溶性鸡肉蛋白规律及其产物清除DPPH活性研究 总被引:1,自引:1,他引:0
研究了Alcalase降解水不溶性鸡肉蛋白的规律及其产物清除DPPH自由基活性。结果表明,随酶解时间延长,可溶性蛋白质、氨基酸含量不断增加,而肽含量则在水解前8h达到最大,随后不断降低;肽的分子量分布趋势总体表现为大分子量的肽逐渐减少,小分子量肽的含量逐渐增多,肽分子量分布图中肽峰值不断向后推移;Alcalase对分子量在3000~15000Da间的肽段降解能力较弱,水解24h后,这部分肽占总肽量的比值仍为89.93%。水不溶性鸡肉蛋白Alcalase酶解产物有明显的清除DPPH活性,其清除DPPH活性在酶解4h时达到最大,随后不断下降;对于同一酶解时间的产物,浓度越大,其清除DPPH活性越强,但其清除DPPH能力并不与酶解液浓度成倍数关系。 相似文献
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采用分光光度法研究了12种植物精油在气相状态下清除DPPH自由基的能力。实验结果显示丁香精油、肉桂精油、茶树油和甘牛至油清除自由基的效果较好,其中丁香精油最好,其次是肉桂精油;延长反应时间、升高反应温度、提高空间精油浓度能有效促进精油对自由基的清除效果。植物精油中的抗自由基活性成分是其清除自由基的关键,高抗自由基活性成分含量越高,其清除自由基的效果也越好;活性成分的挥发性是影响精油气相清除自由基效果的另一个重要因素,高挥发性可使空间精油浓度较高,精油气相清除自由基的效率也就提高。 相似文献
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Formation of pyrazines from ascorbic acid and amino acids under dry-roasting conditions 总被引:1,自引:0,他引:1
Although the participation of ascorbic acid in Maillard-type reactions has been described, the formation of flavour compounds resulting from the interaction of ascorbic acid with different amino acids has not been reported before. Therefore, the formation of flavour compounds from the model reactions of 20 amino acids with ascorbic acid was studied under dry-roasting conditions. Thirty-six different pyrazines were identified, mostly ethyl and methyl substituted pyrazines. The amounts of pyrazines detected were comparable to those formed from pentose sugars. Lysine was the most reactive amino acid and yielded the highest amounts of alkylpyrazines. The reducing activity of ascorbic acid influenced the reaction mechanism of pyrazine formation and thus the type of pyrazines produced. Addition of a base, such as potassium carbonate, significantly enhanced pyrazine formation from ascorbic acid for most amino acids. The formation of pyrazines from serine and threonine without a carbonyl compound was greatly enhanced by the addition of potassium carbonate as well. Furan was detected in all model systems in relatively low amounts and its formation was not enhanced by the addition of potassium carbonate. 相似文献
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目的研究不同外界因素对紫花地丁芹菜素抗氧化稳定性的影响。方法紫花地丁芹菜素标准品经乙醇溶解,采用清除DPPH自由基法测定其抗氧化活性,研究不同pH、温度、光照条件、一些常见金属离子及防腐剂对样品抗氧化性的影响。结果紫花地丁芹菜素具有较强的耐热性;在酸性环境中抗氧化活性保持较好,在碱性环境中抗氧化活性很快丧失;金属离子(Na~+、K~+、Ca~(2+)、Mg~(2+))对紫花地丁芹菜素的稳定性影响不明显,而光照、山梨酸钾则会降低其活性。结论外界环境因素对紫花地丁芹菜素抗氧化能力存在不同程度的影响,建立合适的储存条件可以显著增强紫花地丁芹菜素的抗氧化能力。 相似文献
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后发酵过程中乙醇对豆豉抗氧化能力的影响 总被引:4,自引:0,他引:4
以黄豆为原材料,接种米曲霉制作豆豉,在豆豉后发酵过程中设定了不同乙醇添加量,测定了不同乙醇添加量的豆豉样品清除DPPH(2,2-diphenyl-1-picrylhydrazyl hydrate)及ABTS[2,2-’azinobis-(3-ethylbenzthia-zoline-6-sulfonic acid)]自由基能力、Fe2+螯合能力、还原能力,评价了乙醇对豆豉抗氧化能力的影响。后发酵过程中,豆豉的抗氧化能力持续增大,醇对豆豉的抗氧化能力有影响,发酵相同时间的豆豉,抗氧化能力随乙醇含量的增大而下降。 相似文献
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The efficiency of different white wine antioxidant systems in preventing aldehyde production from amino acids by oxidative processes is not well understood. The aim of this study was to assess the efficiency of sulphur dioxide alone and in combination with either glutathione, ascorbic acid or its stereoisomer erythorbic acid, in preventing formation of the sensorially important compounds methional and phenylacetaldehyde from methionine and phenylalanine in model white wine. UHPLC, GC–MS/MS, LC–MS/MS, flow injection analysis and luminescence sensors determined both compositional changes during storage, and sulphur dioxide–aldehyde apparent equilibrium constants. Depending on temperature (25 or 45 °C) or extent of oxygen supply, sulphur dioxide was equally or more efficient in impeding the production of methional compared to the other antioxidant systems. For phenylacetaldehyde, erythorbic acid or glutathione with sulphur dioxide provided improved inhibition compared to sulphur dioxide alone, in conditions of limited oxygen consumption. The results also demonstrate the extent to which sulphur dioxide addition can lower the free aldehyde concentrations to below their aroma thresholds. 相似文献
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Addion Nizori Lan T. T. Bui Ferry Jie Darryl M. Small 《International Journal of Food Science & Technology》2018,53(6):1363-1370
There has been considerable research into ascorbic acid (AA) as a food component in the human diet and disease prevention. Microencapsulation technology has a promising strategy for enhancing the stability of AA towards the carrier food. The effects of varying hydrocolloid proportions on encapsulation of AA by spray drying have been evaluated. Spray drying pilot plant scale was used to produce the microcapsules, and capillary electrophoresis has been applied to analyse the retention of AA during bread making process. To investigate the characteristics of microstructure of encapsulated AA after processing, the environmental scanning electron microscope was used to investigate the structure of microcapsules. In addition to that to measure the particle size and distribution of microcapsules, the laser beam scattering was used. The impact of varying hydrocolloids proportion on encapsulation of AA by spray drying was studied. 相似文献